citizen science course at ASU

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Month: December 2015

In the past few decades, we have witnessed huge transformations of every day things around us, specially in their physical sizes. A lot has changed from heavy unmovable space-eating giants into highly mobile portable things that fit well in our pockets or backpacks. Computational devices are a prime example for this transformation.

Surprisingly, refrigeration hasn’t evolved into a such highly portable form yet. There is nothing we can carry in our backpacks when we go for an outing to chill our canned beverages or bottles of water. To this end, in this project I propose a cooling mechanism which uses the compressed air as the coolant. If successful this mechanism would enable building portable cooling devices to chill beverages “on-demand” within few minutes. To complement our main theme of “Heat for good”, I decided to present this idea as solar powered chiller, which uses the power generated from solar panels to compress the air.

The cooling mechanism of this device is based on Amontons’ Law of Pressure-Temperature : The pressure of a gas of fixed mass and fixed volume is directly proportional to the gas’s absolute temperature.

With this theoretical back ground I tested the practical feasibility of this system using a simple setup. My test setup was consisted of DC air compressor and a copper tube- one end connected to the compressor. The other end had a valve.

Mechanism:

Air-compressor pumps the air to the copper tube and increase the air pressure inside the tube.

After the inside air pressure reached a desired level, user open the valve allowing the air pressure to decrease drastically resulting a temperature drop. This results a temperature difference between the liquid(beverage/water) and the air inside the copper tube. Therefore a heat transfer will happen from the liquid to air through the wall of the copper tube.

After several failed attempts I was able to use the system to reduce the temperature of water (around 750ml) from 2C degrees. But I couldn’t reproduce the same results because of the problems I had in my setup.

After this initial experiment, I realised even though the concept of the system is somewhat formidable, building a functional prototype is beyond the DIY level because of the following reasons.

Compressor draws around 5A current which is hard to supply from Solar panels.

Difficulties in making the copper tube air tight at the two ends

Difficulties in re-shaping of the copper tube to have a coil shape

Even though, making of a functional system is not feasible, I believe this idea has a potential of becoming a reality at industrial level with tailor-made components and techniques. Because of this, I shifted my focus to speculate on future design possibilities through the following non-functional prototype.

Techniques that benefit human comfort in one climate may be ineffective or even unpleasant in another.

For example, outdoor items, such as benches, playground equipment, and doorknobs, are often made of metal. While this is a durable and sturdy building material, in extreme temperatures it can become so hot as to be literally untouchable. Therefore, a designer should consider what is the temperature range of the area where the item is going to be installed.

Another example is the use of misters, small sprinklers that light spray water into the air, as a means of cooling. In places that are extremely hot with low humidity, the water immediately evaporates, cooling the air. However, in a hot area with high humidity, the water would either not evaporate or just increase the humidity in the area. What was effective in one situation would only cause discomfort in another.

With this in mind, when determining how to design public spaces to keep people cool, we have to look specifically at the climate of Phoenix. Being in a desert, there is very low humidity. The dry air does not hold as much heat, resulting in there being a noticeable change in temperate if one is standing in the shade or direct sunlight. Therefore, an obvious and effective way to help keep people cool outdoors is to keep them in the shade.

However, keeping people shaded is not as simple as it first sounds. Phoenix is built on very flat terrain, so the sun can set far down into the horizon without being blocked by any natural land formation. This is so bad that it often interferes with drivers, as sundown and sunup are considered by many to be the most dangerous time of day due to the decreased visibility caused by the sun. Since morning and evening are often the time when most people want to go out to exercise or socialize, it is important to provide shade for people during these times.

While structures could be built that keep people shaded from the sun in every direction, those would nearly cover the whole area and cause a decrease in airflow. One of the keys to staying relatively cool is plenty of air movement, so a structure that is too covered may block the wind.

Given this environment, we designed prototypes for structures that could be used to shade a large area at all times of the day without blocking airflow. These pieces are designed to change structure over the course of the day to follow the path of the sun. Many of these designs could be implemented in multiple ways, from a high-tech automation to a DIY hand crank.

The animations of these prototypes were created using HTML5 Canvas, which allows the work to be easily viewed across browsers. In addition, because the pieces are composed of vector animation, they can run without being pre-rendered.

Two of the designs were created specifically to be used over large areas such as athletic fields, because of their specific needs. Due to their expansive size, athletic fields often have to be outside. Because the people using it will be engaging in exercise, it is necessary they stay cool. In addition, large groups generally gather at athletic fields in the evening, when it is most convenient for people to find free time.

In one case, the goal was to use shade to create increased privacy in a public space. At sunrise and sundown, the individual shades fold to the side, giving some privacy for the people sitting at each table.

In the other, the shades were variations of blue and green colors, and fold into a shape that resembles lily pads, in order to invoke ideas of water while shading the people below. This hopefully offers some relief from the constant dry, hot temperature that the denizens of the area experience every day.

Data analysis and review. Modify plan according to findings. Write rough draft and rough layout of the survival guide.

Have 1 sample copy of the survival guide for the class demo.

To date, these goals have been accomplished with the exception being the IRB submission. Although the initial questions and IRB submission has been completed, the response from initial field research has altered our course. During preliminary field research with stake holders, it was determined that further study was needed to more precisely target the publication. The initial concept of creating a printed publication for homeless populations was due to the assumption that internet connectivity may be of limited availability to this demographic. During initial discussion with homeless shelter administrators, this assumption was debunked as not applicable to shelter observations. Additionally, it was added that the cel phone has become a primary life-line for “vulnerable” populations and is considered one of the last things given up in a homeless or survival situation.

Although the availability of cel phone and data communications devices does not preclude the development of a survivor guide in general, it does alter the trajectory of behavioral research questions and research design. The use and availability of data communications may suggest an opportunity to deliver a technology, app or website to deliver fresh survival information to vulnerable communities.

It is felt that further field research be conducted in a grass-roots manner and several shelters be visited, volunteer time be committed and true insight into the population be gained prior to submitting a formal research proposal.

In the meantime, resource availability and survival tips, including bio-markers have been identified and documented to support the Survival Guide prototype. Additionally, photo documentation of resources and bio-markers has been achieved and a prototype publication will be produced.

New knowledge has been gained with respect to three important matters:

Phoenix has established an intake organization for managing new homeless cases. Shelters are no longer solely responsible for managing intake and processing of vulnerable families and women.

Phoenix still has not created this intake system for men who are the vast majority of the homeless population in AZ (68-71%)

Homeless populations may have access to and/or use data communication technology and might warrant research specific to this fact.

In addition, new contacts have been made for accessing vulnerable communities in Phoenix for future research.

My initial idea for the DIY Science final project is to build a Solar powered chiller using compressed air. Main idea here is to implement an experimental setup since this idea is facing a heap of implementation challenges.

I received the components needed in the second week of November- a copper tube and a DC air compressor. I tested the practical feasibility of this system using a simple setup. After several failed attempts I was able to use the system to reduce the temperature of water (around 750ml) from 2C degrees. But I couldn’t reproduce the same results because of the problems I had in my setup.

After this initial experiment, I realised even though the concept of the system is somewhat formidable, building a functional prototype is beyond the DIY level because of the following reasons.

Compressor draws around 5A current which is hard to supply from Solar panels.

Difficulties in making the copper tube air tight at the two ends

Difficulties in re-shaping of the copper tube to have a coil shape

Even though, making of a functional system is not feasible, I believe this idea has a potential of becoming a reality at industrial level with tailor-made components and techniques. Because of this, I shifted my focus to speculate on future design possibilities rather than making a fully functional system.